Sprayed soap product



Oct. 28, 1930. STEVENSON ET AL 1,779,517

SPRAYED SOAP PRODUCT Original Filed Aug. 28, 1928 2 Sheets-Sheet 2 Patented Oct. 28, 1930 UNITED STATES PATENT OFFICE EARL P. STEVENSON, OF NEWTON, AND BEN B. FOG-LEE, F BELMONT, MASSACHUSETTS,

ASSIGNORS TO ARTHUR D. LITTLE, INCORPORATED, OF CAMBRIDGE, MASSACHU- SETTS, A CORPORATION OF MASSACHUSETTS SPRAYED SOAP IRQDUGT Original application filed August 28, 1928; Serial No. 302,634. Divided and this application filed December 18, 1929. Serial No. 415,101.

This application is a division of our 00-- pending application entitled Art of spray drying soap and the product thereof, filed August 28, 1928, Serial No. 302,634, and is directed toward the product originally described and claimed therein.

Our improved product is of that class of soap products in which the soap is in the form of discrete hollow particles, and attains the end, among others, of avoiding numerous disadvantages of prior hollow soap products.

Such products exhibited a tendency to form dust during packing and using the soap, which was irritating to the nose and throat of the packers and users. Sodium silicate was incorporated in these soaps to serve as a water-softener, but in practice a large percentage of the originally incorporated sodium silicate appeared in the product atthe time of use in a relatively insoluble form, this percentagebeing of little or no use as a watersoftener and tending to render the wash water cloudy.

These products exhibited increasing percentages of insoluble or diflicultly soluble constituents upon standing in packages, due apparently to the progressive drying of the product, the loss of moisture presumably tending to render more insoluble sodium silicate and silicic acid contained ,within the sea Vl hile hollow granule soapproducts afford the important advantage of quicker solution than chip or shaved soapproducts, and the important advantage of less dusting and sticking together of particles than soap products made by pulverizing or granulating large cakes of soap, the individual particles of former soap products have not been physi; cally constituted in the most advantageous manner for efiicient solution. Soap particles comprising a shell of dry soap surrounding a single principal void have a very great proportion of their constituent material exposed, and relatively little of their constituent material retained within the outer shell. As a consequence, during the heat-drying step in their manufacture the sodium silicate contained within a particle, and lying mostly in and causes it to rise unduly into the suds on thesurface of the wash water. This is undeslrable sincethe action of the soap upon dishes or clothes beneath thesurface is diminished. Furthermore soap particles of this type have been quite bulky, thus increasmg the cost of packing and shipping of a given quantity of available soap.

It has been found that soap products made according to our invention avoid to a great extent the above difficulties and present important advantages over previous soap products.

Our improved product is preferably manufactured according to the art or method described and claimed in our copending application, referred to above, and which will now be explained to enable those skilled in soapmaking more easily to manufacture products embodying our invention. This preferable art or method involves thesteps of-projectmg atomized fluid soap particlesiinto a hot drying fluid wherein they are expanded into a hollowmulti-cellular structure and partially dried by evaporation, separating the hollow but plastic and moist particles from the heated drying fluid after a short travel therein and transferring them to a zone of relatively cool air, and allowing the particles further to solidify in this relatively cool air while retaining their hollow cellular form. This last-mentioned step is referably accomplished with very little if any reduction in moisture content of the soap particles, and may well be carried out in moist conditioned air which serves to raise the moisture content of the particles.

Referring to the accompanyin drawings, which illustrate our new form of a paratus, adapted to perform the process and produce the product in accordance with our invention,

Fig. 1 is a diagrammatic representation of the apparatus as a whole; FFig. 2 is a cross section on line 2-2 of i 1; ig. 3 is a longitudinal section on an enlarged scale of the preferred spraying or atomizing device; and

F i 4 is a dia rammatic representation of y a mogific ation o the spray chamber and associated parts of the apparatus shown in Fig. 1. The apparatus as a whole may be divided generally into the following elements or departments, namely a soap reservoir and circulating system for conducting the fluid soap to the atomizing head; the atomizing head includin a rotating cup into which the fluid soap is ed through a hollow shaft; an air system for supplying heated air at both high and low pressure for atomizing and drying purposes; a horizontal spray chamber in which the initial drying takes place; and a vertical tower for separatin the partially dried soap particles from t e current of heated drying gas and completing the drying to the desired point, and for cooling the particles in a zone of relatively cooler air which may, if desired, be an upward current of cooling air, and/or conditioned air.

When a fluid particle of soap is thrown from the rim of the rotating cup it immediately contacts with a current of heated drying and conveying air, which may be as much as 300 F. hotter than its own temperature. Under this drying potential the evaporation of water at the surface of the partiqle is quite rapid, resulting in an almost instantaneous formation of a semi-solid film through which moisture must diffuse from the interior, in order to evaporate at the surface. Heat is absorbed faster than it can be used u by the surface evaporation of water, wit the result that the temperature within the interior of the particle rapidly increases. When the temperature exceeds the boiling point of water, steam pressure is generated within the particle which is compensated for in part by the expansion of the Th semi-solid, though extensible, surface layer until the point is reached if the expansion is carried far enough, where the film is ruptured and the pressure thus released. A microscopic examination of such particles will almost invariably disclose a blow hole. The

degree to-which this pufiing of the individua particles takes place will depend upon the rate at which heat is absorbed by the particles. In this the controlling factor for a given solution is the temperature of the drying air current. The degree of pulling is proportional to the influent air tempera ture.

Referring now more particularly to the drawings, the soap which is to be atomized and spray dried, is held in solution in water in a supply reservoir 1 provided with heating coils for maintaining the temperature of the soap solution ranging between 160 and 220 F. A satisfactory temperature is about 190 F. The Water content of this solution preferably ranges between and of the total and the solution is of such a consistency as to be readily handled through pipe lines byda pump capable of handling viscous liqui s.

By means of a pump 2 the soap solution is circulated in a closed circuit through pipe 3, returning to the reservoir 1.v Leading from this pipe 3, preferably at a point relatively near the spray equipment, is a feed line at leading to the spray equipment. The amount of soap solution diverted to this feed line may be controlled by valves 5 and 6, which, it is obvious, may be operated to give any desired volume of flow up to the capacity of the pump 2. Incorporated with this soap feed line 4 is a superheater 7 of any preferred type, which provides means for raising the temperature of the soap solution fed to the spraying device to a degree beyond that possible under ordinary atmospheric pressure. This is due to the fact that the soap in this feed line is under the pressures built up by the pump working against-the total resistance of the feed line 4 up to the point at which the discharge takes place at the atomizing device. The soap feed line 4 is also provided with connections for cleaning either with steam or water as shown by the pipes 8 and 9 and the three-way cook 10.

The spraying or atomizing device 11 (showman more detail in Fig. 3) consists of a spinning cup 12 carried upon a hollow rotating shaft 13 driven by a steam turbine 14 or other suitable mechanism for providing a variable speed of rotation. This hollow cup is rotated within a hollow cone or cylinder 15 whose inner surface in conjunction with the outer surface of the spinning cup 12 forms a plenum chamber 16 terminating in an annular orifice 17 surrounding the spinning cup. is plenum chamber 16 is supplied with air at relatively high pressure ranging from 15 to 25 inches of water, and preferably at a temperature ranging from 300 to 450 F by the high pressure fan 18 drawing air through the heater 19 and communicating with the plenum chamber 16 by the duct 20. As here- Ill llf.

inafter explained, it is notalways necessary that the high pressure air should be heated.

The soap is supplied to the atomizing cup 12 by a pipe 2l leading from pipe 4, properly supported within the hollow shaft'13, and terminating in a nozzle 22 so shaped as to deliver the soap solution in a path approximately tangent to the inner surface of the however, opposed or modified by the jet of air issuing from the annular orifice 17 which may be regulated to give a spray cone of any desired angularity of divergence.

The atomizing action obtained by this spinning cup working in conjunction with the annular jet of high pressure air formed by the part 15 is susceptible of producing a wide range of particle sizes which, however, under any given set of 0 rating conditions, tend to be extremely uni orm in size, providing the atomizing capacity of the rotating cup is not exceeded.

For a cup of given diameter and length, the variables affecting the particle size are the angle or contour of the inner face of the cup, the speed of rotation of the cup and the pressure exerted by the air against the sheet of spray as it leaves the edge of the cup. Another factor of importance in the operation of this spraying device is the position of the end 23 of the high pressure cone with respect to the delivery edge 24 of the spray cup. By moving the cone 15 forward so as to be more nearly in line with the edge of the spray cup, high pressure air of a glven head may be made to exert a greater effect in closing in the cone of spray material.

Surrounding the high pressure cone 15 1s a second and larger truncated cone 25 which, in conjunction with the passages leading thereto, forms a plenum chamber 26 for low pressure air supplied by the duct 27 communicating with the main duct 28' which Is fed by the low pressure fan 29 drawlng a1r through the heater 30. This air is supplied at pressures ranging up to 2 inches of water at temperatures between 250 and 400 F.,' the air issuing from this plenum chamber in an annular ring supporting and intermingling with the cone delivered by the spraying device and supplying heat, which may be supplemented by heat contained n the high pressure air, for carrying out the drying operation of the soap particles.

The volume of the high pressure air need be only about 15% to 35%, and is preferably from 20% to 30% of the total volume of the high and low pressure air. The principal function of the igh pressureair jet is to control the form of the spray cone and to furnish the kinetic force to project the spray particles through the horizontal chamber into the ver-- tical tower. Consequently it is possible, if desired, to use unheated air for the high pressure jet, relying on the heat of the larger volume of low pressure air to perform the drying. The recommended temperature of the combined horizontal current of drying air is between 300 and 400 F., and preferably about 325 to 350 F. It is therefore obvious that the temperature of the low pressure air of larger volume may be varied to secure the desired result according to the relative temperature and volume of the high pressure air.

The low pressure heated a1r may also be fed into the drying chamber 31 by duct 28 supplying air through branch duct 30 and port 35 at the rear of the chamber 31 tangential to the surface, this method of tangential entry being that commonly used in the ordinary cyclone separator. The use, or not, of such tangential air is optional.

The spray chamber 31 itself preferably consists of two' principal sections, which,

however, need not be rigidly adhered to in the operation of the process. The section 32 farthest from the spraying nozzle is made up of curved surfaces, the elements of which are parallel to the axis of rotation forming a cross section of inverted pear shape as will be evident from the section shown in- Fig. 2. The upper surface of this section is a true cylinder of approximately six foot radius while the depth of the lower section is approximately twelve feet below the axis of the cylindrical section just mentioned. The rear end wall 33 of the spray chamber is a flat circular plate aproximately six feet in diameter while the remainder, 33, of the spray chamber nearest the spraying nozzle is of a truncated conoidal form of irregular section which can be most accurately described as the surface generated by a line moved about the axis of the spray cone at a uniform angular rate and remaining constantly in contact at one end with the circular back plate 33' and at the other end in contact with the edge of the pear-shaped section 32 at the front.

The spray chamber 31 opens upon a vertical tower 36 whose effective height below the axis of the spray chamber is several times the height of the chamber itself. In practice a cylindrical tower approximately twenty feet in diameter and extending approximately forty feet below the axis of the spray chamber has been found satisfactory.

The vertical tower 36 also preferably extends some distance above the spray chamber as shown. The upper part of the vertical tower above the spray chamber forms a passage for the current of heated air to a suitable flue or vent near the top, and the lower part of the vertical tower below the spray chamber forms a cooling zone into which the particles, separated by gravity from the current of heated air, fall. Since the capacity, or cross-sectional area, of the vertical tower is substantially larger than that of the s ray chamber, it will be seen that the velocity of the current of heated air upon entering the vertical tower will be materially reduced, to a point below the conveying velocity for the denser particles, which are suitable for the finished product, thus permitting the latter to fall by gravity out of the heated air current and into the coolin zone below, while lightest and most expan ed particles which are not desired in the finished product, will be carried on with the air current, although of reduced velocity, through the upper part of the tower to the vent.

The reason for the inverted pear-shaped section of the spray chamber is to provide a means of carrying out of the spray chamber any particles of dried soap which may fall out of the air currents which, in a general way, are moving from the spray chamber into the tower. The sides of the pear-shaped section, as well as the lower half of the conoidal section 33 at the rear, are sufliciently steep to permit the dry particles to slide to the lower surface of the chamber from which they are swept out by a series of air jets 34 which are also supplied with air from the low pressure air duct 28. The heat in this air is also utilized in drying the product as it tends to diffuse through the spray of soap in its natural upward path to the top of the tower.

The function of the tangential air previously referred to as entering the spray chamher by the duct 28, 30, through the inlet 35, if used, is to give a whirl to the entire air within the spray chamber and to sweep clean the inner surface of the latter.

After leaving the spray chamber and entering the tower 36 the soa particles are carried by gravity to the ottom of the tower 36, at which point they may be removed by an air lock 37 or other suitable device which deposits the product in a belt conveyor 38, by which the product may be fed to the packaging machines.

The heated air leaving the spray chamber will, under the conditions shown, have a tendency to rise to the top of the tower, thus freeing the soap from further drying effect of the heated air. The hot air carrying with it the very light, fine and excessively puffed particles, which are undesirable in the fin ished product, passes out of the tower through a flue 39, which may be provided with an air filter 40.

The air in the cooling zone of tower 36 below the spray chamber may be merely quiescent atmospheric air of ordinary room temperatures free from extrinsic current. It is sometimes desirable, however, in order to maintain or modify the condition of the soap particles falling out of the current of heated air into the lower part of the tower 36, to introduce into the tower conditioned air whose temperature and humidity may be controlled to suit the requirements of the product. \Vhile this conditioned air maybe introduced wherever desired in the path of the falling soap articles, it is preferably introduced as by not 41, equipped with a blower 42, near the bottom of the tower, whence it rises in a gentle draft toward the flues 39. An artificially cooled and humidified air will assist in the cooling of the soap product and in retaining in it, or even increasing if desired, the moisture content presentwhen it passes out of the influence of the drying current of heated air.

It should be pointed out that in a tower of relatively large cross section, relatively large volumes of air can be allowed to remain quiescent, or can be moved gently either upwards or downwards in the lower part of the tower below the spray chamber without having any appreciable effect on the falling velocity of the soap particles acting under the force of gravity. Of course conveying velocities should be avoide Instead of venting the hot air at the flue 39 near the top of the tower, it is possible, if desired, to vent the hot air at a point in the tower below the spray drying chamber, thus carrying the drying operation farther along in the path of travel of the product before the product falls by gravity into the cooler part of the drying tower. Thus, it will be seen that the moisture content of the soap particles when they leave the heat drying current of air, may be controlled by terminating or prolonging the influence of the heated air current, as well as by varying the temperature of the air current and/or the water content of the original soap solution.

The,condition of the product made by a spra all tile way from small, comparatively dense and approximately round particles to miniature rather heavy walled spherical soap bubbles, depending on the regulation of the speed of the cup, its shape, the temperatures and volumes of high and low pressure air supplied to the drying chamber and the physical condition of the soap solution itself.

An alternative construction for the horizontal spray chamber may take the form of a truncated cone-like drum, as illustrated in Fig. 4, having a substantially horizontal axis, with the spraying mechanism and air inflow at the smaller end. The flare or angle of the conoidal sides is such that the lower surface 43 of the cone enters the tower at an 'ing process of this nature may be varied an le steeper than the angle of repose of the dried product upon the surface of the material of which the cone is built. This construction automaticallycarries into the tower both theparticles which may drop out of the carrying effect of the, main air currents and also any material which, due to improper operation of the spraying mechanism, may have been plastered on the wall. The latter material puffs into a honeyconibed mass and gradually slips off into the'cooling tower 36 and is insufiicient in bulk to materiall affect the character of the principal pro not of the apparatus. In this construction the stepped jets or blowers 34 in the bottom of the pear-shaped section ofthe horizontal spray chamber of the form shown in Fig. 1,

with their demand for air, are eliminated.

By spraying a very fluid hot soap solution .nto extremely hot air a maximum of ufiing or bubble formation is secured. If this soap is sprayed into cooler air the particles'have less tendency to pufi because the moisture has a chance to evaporate more without undue expansion of the interior moisture, leaving a comparatively round granule. If, however, the soap is allowed to cool before atomizing to the point where it tends to become stringy when dropped, the same tendency will persist to a degree in spraying from the rotating cup giving a rather round particle to which is appended a long stringy tail. Under the violent action of the air currents this tail may be broken up into relatively short pieces of a needle-like appearance. this rather stringy soap is sprayed into relatively cool air the product will consist of a series of relatively large granules mixed with fine needles of varying number representing the broken-up portions of the tails just noted. If, on the other hand, it is sprayed into relatively hot air under the same conditions that produce uniform particles in a more fluid soap, we secure a product made up of rather large approximately spherical pufied articles mixed with elongated pufl'ed particles resembling carrots in their general shape, which appear to be short sections of the tails just noted, and which have likewise been puffed in the same manner that the globules have been puffed. 1

Our copending application, Serial No. 302,633, entitled Apparatus for the spray drying of soap, filed August 28, 1928, contains claims directed toward the invention of which the apparatus explained above constitutes an exemplification.

The fat stocks from which the soap is made may be almost any mixture of tallow and vegetable oils as, for example, a mixture of tallow and cocoanut oil in the proportions of 7 5to 25. Generally, it will be found desirable to use at least 25% of a hi h titre stock, such as tallow. Palm oil can e used in part as a substitute for tallow in-the above formula.

soda ash, sodium phosphate, "silicate of soda, etc. A soap composition satisfactory for'our purpose is one containing 60 parts pure soap 25 parts soda ash 15 parts sodium silicate.

The product is preferably made by spra mg fluid soap stock preheated to 180200 and containing 40% water and 60% of solids, for example, soap composition as above formulated, on an anhydrous basis. In handling such a formula in an a paratus of the dimensions heretofore speci ed as suitable for the purpose of practical operation it is recommended that the drying air be preheated to approximately 325350 F., and that in spraying at the rate of 4,000 pounds per hour of finished roduct, there be used upwards of 20,000 cu ic feet of hot air per minute. Under these conditions the finished I product should have a gravity at least as high as .3 compared to water.

The physical structure of the individual particles made under these conditions should consist of an outer shell only'moderately extended or puffed, and not so unduly extended as to produce undesirable bulk, the interior f having therein thin films or walls which de- 72.3 parts pure soap 6.3 parts soda ash 21.4 parts sodium silicate has been employed to manufacture a sprayed soap product having the chemical composition of approximately The bulk weight of the product will usually be approximately 20 pounds per cubic foot, but may be more, and under the operating conditions explained above will certainly be more than 15 pounds per cubic foot and will contain 15% or more, preferably soap soda I ash sodium silicate water.

about 20% (for instance 18%) of water. It

will be apparent, however, that the. advantages ofv this high moisture content may be realized separately from the advantages of high bulk weight and multi-cellular structure and that the novel and advantageous property of high moisture in a soap 0 this puffed character is not dependent upon high bulk weight or multi-eellular structure.

Our ufied soap product can readil be distinguis ed from aerated soap pro ucts of either shredded or cake form in which air has been incorporated by agitation for the purpose of causing the'product to float.

These so-called aerated soap products are substantially solid'and homogeneous masses containing microscopic inclusions of air which have been caught within the soap at the time of solidification. Such microscopic air inclusions do not make a roduct which can be described as having wa ls, or as bein generally hollow. As contrasted with this, the characteristic ufi'ed structure of our product is attained through the ex ansion of steam within the soap particle. his expansion of the interna ly generated steam causes a rapid expansion or pufling of the entire particle somewhat analogous to the blowing of soap bubble. The walls of the particle become extended and thin relative to the surrounded volume. This in itself is advantageous in causing the soap to dissolve rapidly. In the dissolving of our products water rapidly gains access through the relatively large internal cavities to the relatively thin and extended soa walls which, because of their thinness an largle specific surface, dissolve rapidly. The igh moisture percentage still urther accelerates solution. Our product preferably contains at least 15% of water, and may well contain more, as exemplified by the compositions of the finished soap products givenabove. The presence of this high ercentage of water in the product has been ound to be of great utility in retaining the silicate in the soap (which is intended to perform the function, among others of a water-softener) in an easily soluble state.

As is well known, sodium silicate may exist in either a hydrated or a dehydrated form. odium silicate in drying out from an aqueous solution becomes progressivel less and less readily soluble in water; an will generally assume a dehydrated form which is practicall valueless as a detergent or water softener. n our improved product, the high percentage of moisture retained in the product keeps the sodium silicate, in the more ighly hydrated, readily soluble, form. The inclusion of the relatively high percentage of water serves to render the sodium silicate content readily soluble, and further prevents any subsequent drying of the product during shipping and stora e from unduly decreasing the rate of solubility of the sodium silicate.

The ability of the high water content of our product to maintain the sodium silicate in an easily soluble state permits the advantageous incorporation in a puffed coap of hi her percentages of sodium silicate than ormerly. As illustrative ofthis higher range of sodium silicate, a ufied soap has been made according to our lnvention containing approximateg with voids between. Because of the soap contained in these inner walls, the particles of such a product contain a higher proportion of available soap than hollow particles having a single inner void. This provides a more compact, heavier particle which does not rise unduly fast in the wash Water and in which the tendency to climb into the suds is diminished. A more eflicent dissolution is therefore obtained since the particles have more opportunity to form soap solution in the body of the wash water in contact with the dishes or clothes, and less tendency to form a bulky suds floating on the surface of the water. Unnecessary and excessive bulk either in the material handled for packing, or in a package of given weight, is obviated.

It has been found that our improved product exhibits less tendency than previous pufied soap products to form dust which irritates the nose and throat. We attribute this advantageous result to the high moisture content of the roduct which renders the particles less britt e and less liable to disintegrate in handling, and in part to the compact multicellular structure of the particles which gives a smaller ratio of exposed surface to available weight of soap and which enables smaller bulks of the product to be used in place of larger bulks of previous pufi'ed soaps.

When, as explained, our product is made in its preferable relatively compact heavy-bulking form, its rate of solubility is not accurately comparable to previous more highly-puifed products having a higher ratio of exposed surface to weight of soap. However, its rate of solution is rapid and entirely adequate for all purposes. That the high moisture content contributes appreciably to the rate of solubility of the soap is certain since experiments have shown that the rate of solubility of a product made according to our invention, and containin for example 18% of water, is considerablyiigher than that of an experimentally manufactured product of similar particle structure, but containing only 12% of water.

\Ve claim:

1. As a new article of manufacture, a soap product made up mainly of discrete particles having a void-defining soap shell structurally characteristic of puffed spray dried soap, the

soap substance of the particles containing at least 15% of moisture.

2. As a new article of manufacture, a soap product made up mainly of discrete particles having a void-defining soap shell structurally characteristic of puffed spray dried soap, the soap substance of the particles containing approximately 20% of moisture.

3. As a new article of manufacture, a soap product made up mainly of discrete particles having void-defining soap walls structurally characteristic of pufi'ed spray dried soap, the soap substance thereof containing at least 15% of moisture, the product havin a bulk yfveight of at least fifteen pounds to tie cubic oot.

4. As a new article of manufacture, a soap product made up mainly of discrete particles having void-dehnin soap Walls structurally characteristic of pufied spray dried soap, the

soap substance thereof containing approximately 20% of moisture, the product having a bulk weight of approximately twenty pounds to the cubic foot.

5. As a new article of manufacture, a soap product made u mainly of discrete particles having void-de ning soap Walls structurally characteristic of puffed spray dried soap, the soap substance thereof containing approximately 20% of moisture, the product having a bulk weight of at least fifteen pounds to the cubic foot.

6. As a new article of manufacture, a soap product made up mainly of discrete particles having a void-defining soap shell structurally charactertistic of pufied spray dried soap, the soap substance of the particles containing at least 15% of moisture, containing sodium silicate, and containing substantially no 46 Water-insoluble silica compound.

- 7. As a new article of manufacture, a soap product made up mainly of discrete particles having void-defining soap walls structurally characteristic of puffed spray dried soap, the

50 soap substance thereof containing approximately 20% of moisture, containing sodium silicate, and containing substantially no water-insoluble silica tompound, the product having a bulk weight of at least fifteen pounds to the cubic foot.

Signed by us at Boston, Massachusetts, this 17th day of December, 1929.

EARL P. STEVENSON.

BEN B. FOGLER.

DISCLAIMER 1,779,517.--Ea1-Z P. Sterensen, Newton, and Ben B. Fogler, Belmont, M ass. SPRAYED SOAP PRODUCT. Patent dated October 28, 1930. Disclaimer filed March 21, 1934, by the assignee, Lever Brothers Company. Hereby enters this diselainer to claim 1 of the above identified patent, and also enters this disclaimer to claim 2 of said patent save and excepting when the product defined 1n said claim 2 contains a substantial am [Ofiicial Gagette April 10, 1984.] 

